Filtration of a fluid, such as a gas in a compressed gas system is generally required so that the fluid is sufficiently free of contaminants (liquid, solid or gaseous) for a subsequent application or to minimise adverse effects of contaminants on components of the system. For example, removal of compressor oil from a compressed gas stream can be required to minimise chemical contamination and accumulation on valves which might lead to malfunction of the valves. It is known to treat a fluid stream to remove contaminants (liquid, solid or gaseous) by filtering the fluid stream, using a filter element, also known as a coalescing filter. It is also known to treat a fluid stream by imparting a helical flow to fluid entering the filter assembly, using a flow director, so that centrifugal forces causes separation of bulk liquid or solids, such as water, from the stream.
Filter assemblies typically comprise a housing comprising head and body parts, and a filter element which can be fitted within the housing. Such filter elements commonly have a wall of a filtration medium and an end cap with an inlet which can be sealed to the head part of the housing to provide a flow path for a fluid stream to be supplied to the space within the filter element. The inlet is provided by a port on an end cap of the element. The port has an O-ring seal on its external surface which is received in a bore within the housing end cap, in which it is compressed to form a seal.
It is important to ensure that the head and body parts of the housing are correctly fitted together before operation of the filter assembly. This is because if the head and body parts are not properly secured to each other, then there is a significant risk that the head and body will break away from each other due to the high internal pressures that the housing is under during operation of the filter assembly. This can be dangerous because the head and/or body part can be forced away from the filter assembly at high velocity which can cause damage to apparatus or users close to the housing.